Marine propulsion means



"Ma 17, 1960 H. KUTTNER 2,936,729

MARINE PROPULSION MEANS Filed Nov. 8, 1955 IN V EN TOR.

- Patented May 17, 1961) 7 MARINE PROPULSION MEANS Hugo Kiittner, Graz, Austria Application November s, 1955, Serial No. 545,651

Claims priority, application Austria November 18, 1954 7 Claims. 01. 11s-,-2s)

"In ships of the usual construction, which are driven either by paddle wheels fitted to the side of the hull or by screws mounted at the stern of the hull, the comparatively big wash forms a considerable component of the resistance to motion. The wash isdirected against the ity of the ship, it prevents an increase in velocity beyond a certain limit, particularly in submarines and the like.

The invention is based on appreciation of the fact that these disadvantages can be avoided and a considerable increase in velocity can be attained without over dimensioning the motive system if the swinging stern of the ship'itself is made in one piece from an elastic material such as rubber and/ or has at least one elastic longitudinal member extending throughout its entire length, so that the stern forms an even continuation on all sides of the substantially inflexible remaining portion of the hull, at

least under the water line. The longitudinal member can be an extending leaf spring, e.g. a central steel plate, or an ash wood spring. In principle, the elastic stern of the invention acts as does the tail fin of a fish. The eificiency of such a drive is better than that of the usual ship constructions, as evidenced by comparing the highvelocities of small fish.

hull and which are oscillated by means of a lever, are

'known, but in these ships, which were mainly used as toys, the pliable tails were made of transverse members and were relatively little elastic. With transverse members special steps must be taken to seal the individual members with one another. The members have to overlap partly or a folding bellows must be provided between 2 tion of the invention; Figs. 9 andxlO represent a further modification of the tail; and Fig. 11 is a longitudinal sectional view along the lines of Fig. 3 showing the dis? position of the eccentric masses. 7

According to Figs; l and 2, the streamlined hull 1, the upper portion of which has bullseyes 2 above the water line 3, is closed at the rear by a transverse wall 4. The elastic stem 5 is attached to this wall, which stern tapers rearwardly and the outer faces of ,which are flush V in Figs. 3 to 6, namely, at least one longitudinal leaf spring 7 surrounded by an elastic filler 8,. preferably of soft rubber, and an outer shell 9. The spring has anopening 10 (Fig. 3) which determines the height of a Ships having pliable fins attached to the stern of the cavity" 11 in which the drive mechani'sm' is mounted, e.g=.l anelectric motor 12, having a mass rotatingii about ant parallel to the direction of motion and not passing through the center of gravity-of the mass. The motor 12 is preferably movable longitudinally of the stern and mounted on the extending leaf spring 7 by guide elements 13 (Fig. 3). Several drive mechanisms could be arranged one behind the other. The frequency of oscillations of the eccentric masses preferably equals the natural fre quency of the oscillations of'the tail fin.

Steel stays 14 preferably are provided to strengthen the cavity, in particular between the points of mounting of the drive mechanisms. These stays are likewise mounted on the leaf spring 7 by guide elements 13. As-

shown in Fig. 6, they may be'single limbed and arranged oppositely off-set on both sides of the longitudinal memher, or they may have two arms.

Figs. 7 and 8 show a different embodiment of the invention, in which the stern comprises several elastic longitudinal members 15 formed'from spiral springs,

A further modification of the stern is shownin Figs.

9 and, 10. A. barrel-shaped spiral spring 16 within a filler forms the elastic longitudinal member, which tapers rearwardly and leaves a cavity in the centre for mounting a drive mechanism of the kind indicated. As shown in Fig. 10, the motor is suspended from the turns of the them. This necessarily results in an uneven surface which causes the oscillating action of the tail members to be unharmonic. In other known ships only the rudder or a separately attached fin, but not the stern, is formed elastically. Rudders or fins always have a very small thickness. Thus, strong eddies are created and the efficiency is low. According to the invention, however, a smooth, uninterrupted outer surface and an even course of the stern are ensured, which closely resembles the example set by nature and results in an improved efliciency.

Several embodiments of the invention are illustrated inthe drawings, wherein Figures 1 and 2 are a plan-and side elevation of a speed boat; Fig. 3 is a longitudinal secspring anddirectly transmits the oscillations to the tail. This embodiment is simple and strong- It has the advantage that stays as shown in Fig. 6 are eliminated.

The attachment of the stem to the other part of the hull can'be preferably by way of fastening elements embedded or moulded in the stern. The outer shell consists of a tight, wear-resistant rubbery material which is joined to the softer filler e.g. by vulcanizing.

By virtue of the combination of the elastic material with the springy longitudinal members, the elastic stern constructed according to the invention results in a favourin area from its forward end a ft at least below the water 7 line, and a propelling mechanism associated with the stern part and acting only in the forward part of the stern part.

t 2. A ship structure as claimed in claim l'wherein the stern part includes a leaf spring extending within and centrally of the stern part. 1

3. A ship structure as claimed in claim 1 wherein the stern part includes 'a plurality of spiral springs extending lengthwise Within the stern part. 7 V

4. A ship structure as claimed in claim l-wherein the stern partincludes a plurality of rubber rolls extending throughout the entire length of the stern part.

part and actingronly inthe forward part of the 'st'ern part,

and a barrel-shaped spiral? spring tapering aft within the stern part. g r a 6. A ship structurecomprising a hull including a fore part and an oscillatable stern part connected to the fore I part, said stern part being of elastic one piece material v pelling mechanism being, an electric motor mounted in such opening for movementlengthwise of the opening.

7. A ship structure as claimed in claim 6 further including stays fastened to the said leaf spring and bracing the said opening. v

ReferencesCited in the file of this-patent w 7 UNITED STATES PATENTS 443,991 Ellis Jan. 6, 1891 621,719 Shann Mar. 21, 1899 1,324,722 Bergin Dec. 9, 1919 2,432,869 Elmer Dec. 16,1947 FOREIGN PATENTS l 126,231 Great Britain May 8,1919 301,446 Germany Oct."'19, 1917 733,446 Germany Mar. 26, 1943 

